Defer layer rendering to avoid stalls

Bug #7326824

When a layer is taken out of the cache and initialized it gets cleared
to prepare it for future rendering. This triggers the following sequence
of operations:

glBindFramebuffer(layer.fbo)
attach texture storage to FBO
glClear()
glBindFramebuffer(defaultFbo)

The clear forces a resolve on tilers which stalls the CPU for a little
while, thus producing jank during animations. This change moves the
clear to the next frame when we know we will have to execute a resolve
anyway.

Change-Id: Ic1939c25df20ed65a4c48dc81ee549b2cd8b6ec3

1 files changed, 1 insertions, 0 deletions

diff --git a/libs/hwui/Layer.cpp b/libs/hwui/Layer.cpp
index 882e4bbc4bb1..1cdc06306be4 100644
--- a/libs/hwui/Layer.cpp
+++ b/libs/hwui/Layer.cpp
@@ -31,6 +31,7 @@ Layer::Layer(const uint32_t layerWidth, const uint32_t layerHeight) {
     meshIndices = NULL;
     meshElementCount = 0;
     cacheable = true;
+    dirty = false;
     textureLayer = false;
     renderTarget = GL_TEXTURE_2D;
     texture.width = layerWidth;